1. Field of the Invention
The subject invention generally pertains to electronic power conversion circuits, and more specifically to high frequency, switched mode power electronic converter circuits.
2. Description of Related Art
Power conversion circuits, in general, create either a pulsed current wave form or a continuous triangular wave form at the terminals of the circuit. To provide an electromagnetically compatible interface filters are often provided at the terminals. The size and cost of the filters depends on the frequency content and magnitude of the AC ripple components of the terminal currents. A terminal with a pulsed current wave form almost always requires a filter and a triangular terminal current wave form may require a filter although one much smaller than would be required by a pulsating current. In addition to the terminal filtering schemes there are ripple current steering schemes that add windings to the chokes and transformers and capacitors to provide a preferred path for AC currents away from the terminals. New techniques for changing converters with pulsating terminal currents to equivalent circuits with non-pulsating terminal currents have recently been revealed. The process for converting a three terminal power conversion network with pulsed terminal currents to an equivalent network with non-pulsating terminal currents is illustrated in FIG. 1. A new process has been developed which further converts a three terminal network with pulsating terminal currents into a three terminal network with ripple current cancellation at each terminal. This new process is the subject matter of this invention. The new process revealed here eliminates to a first order approximation all the ripple current thereby providing a circuit with high electromagnetic compatibility.
The process illustrated in FIG. 1 applies to all three terminal networks in which there is an inductor in series with one of the three terminals in which the terminal containing the inductor is non-pulsating which is always the case when the inductor is uncoupled. FIG. 25 illustrates a tapped inductor three terminal network which has a coupled winding in series with one terminal. Applying the process illustrated in FIG. 1 to the tapped inductor cell yields the networks illustrated in FIGS. 26 and 27 in which the terminal currents are all pulsating and there is no improvement. We will show how the FIG. 27 network can be transformed into a network in which the terminal currents are non-pulsating at all three terminals and the terminal ripple current is canceled at all three terminals.
FIG. 41 illustrates a three terminal network which has one inductor but the inductor is not connected to any network terminal. This network has pulsating current at all three terminals. A generalization of the FIG. 1 process can yield a network with non-pulsating current at all three terminals and ripple cancellation at one of the three terminals.
Isolated active reset circuits with zero voltage switching have been known for some time, but all of these circuits suffer from pulsating input terminal current. Isolated active reset circuits that achieve zero voltage switching use the reversal of the magnetizing current in the main transformer or coupled inductor or a series inductance in the form of leakage inductance or a discrete series choke to drive the resonant transitions. By splitting the windings and rearranging the primary circuits these also can be made to have zero input terminal current ripple.
One object of the subject invention is to provide simple DC to DC power conversion circuits with both ripple free input current and ripple free output current using a single simple magnetically coupled inductor.
Another object of the subject invention is to provide a simple non-inverting ripple free step down DC to DC power conversion circuit.
Another object of the subject invention is to provide a simple non-inverting ripple free step up DC to DC power conversion circuit.
Another object of the subject invention is to provide a simpler circuit topology that can achieve zero ripple at all terminals with buck, boost, or buck boost (flyback) transfer functions, thereby enabling converters with smaller cheaper inductors and capacitors and converters with superior transient response and superior EMI performance using a single coupled inductor.
Another object of the subject invention is to provide single active switch quadrature converters with ripple free terminal currents for applications with wide input or output voltage ranges.
Another object of the subject invention is to provide boost complement, flyback complement, and buck complement converters with ripple free terminal currents using a single coupled inductor.
Another object of the subject invention is to provide tapped inductor buck, boost, and flyback converters with ripple free terminal currents for applications with very small or very large duty cycles using a single coupled inductor.
Another object of the subject invention is to provide isolated active reset converter circuits with input terminal current ripple cancellation.